The rate of diabetes in patients with PD was 16.5% in our study. It is similar to previous literature reports. The cause of ESRD was diabetic nephropathy in 16.4% of patients in China 12. We found that in 44.03% of patients, serum HDL-C levels decreased during the course of our study. A total of 7.1% of diabetic patients also had low HDL-C levels in our study. We found that low HDL-C levels alone or diabetes alone were not independently associated with the first episode of PDRP in patients. Diabetes and concurrent Low HDL-C levels were associated with the first episode of PDRP in patients with PD in our study.
It is reported that the PDRP rate was higher in DM patients than in non-DM patients 13. Diabetes alters the immunity of peritoneal defences, such as leukocyte adherence, chemotaxis, and phagocytosis. Diabetes also interferes with the migration of phagocytic cells into the peritoneum and suppresses the phagocytic activity of resident peritoneal macrophages 14. Not all study supported the conclusion. Some studies found that diabetes was not an independent risk factor for PDRP 15 16.- Hyperglycaemia was reported to be a predictor of risk for tunnelled catheters and existing infections but not for peritoneal infections 17. Diabetes was not an independent risk factor for PDRP in our study. Low HDL-C levels were seen in diabetes patients. Lack of apo AI and apo AII and increased clearance of HDL are the main reasons for low HDL-C levels in diabetes. HDL plays an important role in fighting infection in many ways. HDL binds and neutralizes gram-negative bacterial lipopolysaccharide (LPS) and gram-positive bacterial lipoteichoic acid (LTA). HDL inhibits adhesion molecule expression induced by proinflammatory cytokines after inflammation, such as V-CAM-1, ICAM-1, and E-selectin. HDL may also prevent monocyte activation and recruitment. As a result, the inflammatory response decreases after sepsis. HDL limits oxidation by decreasing ROS production and inhibiting LDL oxidation. Low HDL levels lead to a decrease in antioxidation and exacerbate damage from infection 18. Low HDL levels are a risk factor for foot infection in diabetic foot osteomyelitis 19. Low HDL levels were also associated with parasitic disease and Mycobacterium tuberculosis infection in diabetic patients 20 21. Finally, low HDL levels were seen in periodontal infection in diabetic patients 22. All these reports demonstrated that diabetes coexisting with low HDL-C levels were associated with infection. HDL-C binds to pathogenic microorganisms and reduces inflammatory damage in diabetes. PDRP is a typical bacterial infection in patients with PD. Diabetes plus low HDL-C levels increased the risk for PDRP in patients with PD in our study. The K-M curves confirmed the result. It is therefore important to maintain normal serum HDL levels in diabetic patients with PD.
PD patients usually show increased levels of triglycerides (TGs), cholesterol (CHOL), and low-density lipoprotein - cholesterol(LDL-C) and decreased levels of HDL -C 23. Since disorders of HDL-C are associated with severe infection and exaggerate the systemic inflammatory response 24 25 26, we analysed the association between HDL-C level and PDRP in patients with PD. We found low HDL-C levels were not independently associated with PDRP in PD patients in our study. The reason might be that dyslipidaemia is a complicated process in patients with PD. Disorders of TG, CHOL and LDL-C also participate in the pathological process of PDRP. Low HDL-C levels alone were not enough to be an independent risk factor for PDRP in our study.
In previous studies, dyslipidaemia and poor glycaemic control were reported to be risk factors for ESRD and mortality in young patients and women27–29. HDL-C was inversely associated with left ventricular mass index in patients with PD30. Subgroups of age, sex, and history of cardiovascular disease were analysed in our study. We found that the association between DM plus low HDL-C levels and PDRP was not affected by age, sex, or history of cardiovascular disease after adjusting for age, sex, body mass index, current smoking, Pre-existing stroke,Pre-existing CVD,Statins and laboratory tests except the subgroup variable. We confirmed that DM plus low HDL levels is an independent risk factor for PDRP in patients with PD.
Our study has several limitations: 1. our study is a retrospective, multicentre study that possible had selection bias; 2. our study only looked at the association between DM plus a low level of HDL-C and PDRP. We could not determine the causality relationship between DM plus low HDL-C and PDRP; 3. TG, CHOL, and LDL-C levels were associated with HDL-C levels, and we should detect the detailed relationship between TGs, CHOL, LDL-C, and HDL-C in patients with PD and evaluate the effect of the interaction between HDL-C and other lipids on PDRP.